Summer vacation represents a 3-month window of time youth spend away from the daily responsibilities and scheduled demands experienced during the 9-month school year. Only recently has the change in summer behavior patterns been suggested to have a potentially negative impact on the health behaviors of youth. Evidence is mounting that children gain three to five times more weight over the 3-month summer vacation than the amount of weight gained during the entire 9-month school year and that fitness gains achieved during the school year are erased over the summer months. What children eat and drink, the types of physical activity opportunities they are afforded, and the amount of screen-time and sleep (two important correlates of weight gain) they engage in during the summer months is unknown. Children from ethnic-minority and low-income households are most at-risk for unhealthy weight gains during summer compared to White non-Hispanic children and high-income households. Despite decades of attention to youth obesity and associated health behaviors, very limited attention has been given to the health effects of summer vacation. Research is needed that investigates what youth do outside of the school year, the location of these activities, and the foods/beverages consumed. The proposed study will be the first to systematically collect physical activity, dietary, sleep, and sedentary behavior information on a cohort (N = 504) of African American children from low- and high-income households and White non-Hispanic children from low- and high-income households (4 groups) beginning the spring of 1st/3rd grade and continuing through the fall of 3rd/5th grade. State-of-the-art assessments will be collected routinely during the school year and summer to compare differences in behaviors during these two important time periods across these two groups of children. We will also collect detailed information regarding the home, school, and community environments and examine their associations with physical activity; sedentary, sleep, and dietary behaviors; and changes in BMI during school and summer. We will use a 3yr longitudinal observational study and complete the following specific aims: Aim 1. Compare changes in BMI z-scores during school (beginning of fall to end of spring) and summer (end of spring to beginning of fall) between children across race and income levels; Aim 2. Compare differences in physical activity, sedentary, sleep, and dietary behaviors between the school year and summer between children across race and income levels; Aim 3. Compare changes in physical activity, sedentary, sleep, and dietary behaviors to changes in BMI z-scores between school and summer between children across race and income levels; Aim 4. Identify individual, family/home, neighborhood, and school/community influences on children?s BMI z-scores, physical activity, sedentary, sleep, and dietary behaviors during school and summer between children across race and income levels.